Lift anchor for concrete panel

ABSTRACT

An anchor for use in a concrete panel that has a shank with four sides forming a substantially square longitudinal cross-section. One end of the shank is connected to a foot and is embedable in the concrete panel. An opposite end of the shank is connected to a head and is locatable in a recess in the concrete panel.

FIELD OF THE INVENTION

[0001] This invention relates generally to anchors for lifting heavy loads and, more particularly, anchors of solid material that are embedded in a concrete member.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to an anchor for lifting a concrete panel by its edge or face. Such a panel is often formed by pouring concrete into a form or mold at floor level either at, or remote from, a construction site. After the concrete has set or hardened, the horizontal panel is first lifted by its face from the form; and then, the concrete panel is lifted by one end and tilted upward until it is vertical. Thereafter, the concrete panel can serve as a wall of a concrete building.

[0003] Heretofore, in the production of tilt-up concrete members or panels that are to be handled with a face-lifting or edge-lifting operation, it is the practice to embed anchors of steel or iron in the concrete panel. A known round lift anchor has a cylindrical rod with a circular head at one end and a circular foot at an opposite end. In a face-lifting application, the circular foot is embedded in a major surface or face of the concrete panel such that the circular head is located in a recess in the face of the concrete panel. When lifting operations commence, the cylindrical rod of the partially embedded anchor is subjected to significant tensile forces. While known anchors perform well, there is a continuous effort to improve the lifting capacity of such anchors.

SUMMARY OF THE INVENTION

[0004] The present invention provides a lift anchor that has improved section properties to better resist axial and bending forces and thus, has a greater lifting capacity than known comparable anchors. The lift anchor of the present invention is especially useful in lifting a concrete panel by its face.

[0005] According to the principles of the present invention and in accordance with the described embodiments, the invention provides an anchor for use in lifting a concrete panel. The anchor has a shank with four sides forming a substantially square longitudinal cross-section. One end of the shank is embedable in a concrete panel, and an opposite end of the shank extends into a recess in the concrete panel. The anchor further has a foot connected to the one end of the shank and a head connected to the opposite end of the shank. The foot is thus embedable in the concrete, and the head is locatable in the recess in the concrete panel. In one aspect of this invention, the lift anchor is forged from a single piece of square bar stock.

[0006] These and other objects and advantages of the present invention will become more readily apparent during the following detailed description taken in conjunction with the drawings herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1 is a side elevation view of a lift anchor in accordance with the principles of the present invention.

[0008]FIG. 2 is a cross-sectional view of the lift anchor taken along line 22 of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0009] Referring to FIGS. 1 and 2, a lift anchor 20 is comprised of a body 22 having a shank 28 with one end 30 rigidly connected to and integral with a head 24. An opposite end 32 of the shank 28 is rigidly connected to and integral with a foot 26. The shank 28 has a substantially square longitudinal cross-sectional area 29 (FIG. 2). Thus, the shank 28 has four substantially mutually perpendicular sides 36, 38, 40, 42 of substantially equal length that define a width of the shank. Further, the square longitudinal cross-sectional profile of the shank extends over substantially a full length of the shank 28.

[0010] As used herein, the term “longitudinal cross-section” means a cross section of the shank 28 taken in a plane substantially normal to a longitudinal centerline 34 of the shank 28. The term “centerline cross-section” means a cross-section of the shank 28 taken in a plane that contains the shank centerline 34.

[0011] The anchor head 24 has an outer substantially cylindrical portion 44, and a head transition 46 that connects the cylindrical portion 44 with the shank end 30. The head cylindrical portion 44 has a diameter that is greater than the length of the sides of the shank 28. The head transition 46 has a substantially circular outer edge 48 that has a diameter substantially equal to the diameter of the cylindrical portion 44. An inner edge 50 of the head transition 46 has a diameter about equal to the width of the shank 28, that is, the length of the shank sides 36-42. In a centerline cross-sectional profile of the shank, the head transition 46 is curvilinear and more specifically, circular. Thus, the surface 52 of the transition 46 is partially spherical in shape.

[0012] The foot 26 is similarly shaped to the head 24 and has an outer cylindrical portion 54 that is connected to the opposite end 32 of the shank 28 by a foot transition 56. The foot cylindrical portion 54 has a diameter that is larger than the diameter of the head cylindrical portion 44. The foot transition 56 intersects with the cylindrical portion 54 along a circular outer edge 58. The foot transition 56 intersects with the shank opposite end 32 along a substantially circular inner edge 60. As with the head 24, in a centerline cross-sectional profile of the shank, the foot transition 56 is curvilinear and more specifically, circular. Thus, the foot transition 56 provides a surface 62 that is partially spherical in shape.

[0013] The lift anchor 20 is drop forged from a piece of square carbon steel bar stock, for example, grade C-1045. Thus, the head 24, foot 26 and shank 28 form a single integral body 22. In one embodiment, the lift anchor 20 is formed from square bar stock having a nominal shank width of 0.75 inches. As will be appreciated, depending on the application and designed load carrying capacity, the anchor 20 may vary in length and may be manufactured from square bar stock having different nominal sizes.

[0014] In use, a concrete panel is often fabricated in a mold in a generally horizontal position and must be lifted by its face to remove it from the mold. To facilitate that face-lifting operation, the lift anchor 20 is molded into a face 65 of a concrete panel 66. The face 65 is one of two substantially parallel opposed surfaces of the concrete panel 66 and thus, the anchor 20 extends across a thickness of the concrete panel 66 as represented by the arrow 68. The face 65 has a generally spherically shaped void 76 containing the lift anchor head 24.

[0015] Prior to molding the concrete panel 66, the lift anchor 20 is supported and oriented in a substantially vertical position in a known manner in a concrete form or mold (not shown). The following discussion with respect to the lift anchor 20 applies to other anchors substantially identical to the lift anchor 20 that may be required to lift the concrete panel 66 by its face.

[0016] A void mold 74 is used to form the cavity or void 76. The void mold 74 is mounted at the shank outer end 30. Referring to FIG. 2, the void mold 74 has an opening 78 with a square longitudinal cross-section that is sized to fit around the perimeter of the square longitudinal cross-sectional area 29 of the shank 28. The square cross-sectional profiles of the shank 28 and opening 78 permits the void mold to be mounted and secured at a desired orientation; and the void mold 74 is unable to rotate with respect to the centerline 34. In contrast, with a cylindrical shank, the void mold is able to rotate on the shank; and other steps must be taken to secure the void mold in its desired orientation. After the void mold 74 is mounted on the shank 28, the concrete is poured into the concrete form in order to produce the concrete panel 66 with the lift anchor 20 disposed therein. After the concrete sets, the void mold 74 is removed in a known manner; and the head 24 is left disposed in the cavity 76.

[0017] Subsequently, a lifting device (not shown) is hooked under the head 24 within the cavity 76; and a lifting force is applied to the lift anchor 20 such that the face 65 of the concrete panel 66 is moved generally vertically upward as viewed in FIG. 1.

[0018] The square shank lift anchor 20 provides a substantial advantage over a comparable known cylindrical shank lift anchor. The square longitudinal cross-section of the shank 28 provides an area that is larger than a cylindrical cross-section of a cylindrical shank lift anchor of the same nominal size. That is, a square shanked lift anchor made from 0.75 inch square bar stock has a larger longitudinal cross-sectional area than a cylindrical shank lift anchor made from 0.75 inch round bar stock. Thus, the square shank 28 is stronger than its comparable cylindrical shank and is less likely to bend.

[0019] While the invention has been illustrated by the description of one embodiment and while the embodiment has been described in considerable detail, there is no intention to restrict nor in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those who are skilled in the art. For example, in the described embodiment, the head 24 and foot 26 are illustrated and described to have a generally circular shape. As will be appreciated, there may be lift anchor applications where it is desirable that the head 24 and/or the foot 26 have a different configuration or shape. Further, in the described embodiment, the lift anchor 20 is used to lift a concrete panel 66 by its face 65. As will be appreciated, in other applications, the anchor 20 and an associated recess can also be molded in an end surface of the concrete panel, so that the anchor 20 can be used in an edge-lifting operation.

[0020] Therefore, the invention in its broadest aspects is not limited to the specific details shown and described. Consequently, departures may be made from the details described herein without departing from the spirit and scope of the claims which follow. 

What is claimed is:
 1. An anchor for use in a concrete panel having a recess in a surface of the concrete panel, the anchor comprising: a shank comprising four sides forming a substantially square longitudinal cross-section, one end adapted to be embedable in the concrete panel, and an opposite end adapted to extend into the recess in the concrete panel; a foot connected to the one end of the shank and adapted to be embedable in the concrete panel; and a head connected to the opposite end of the shank and adapted to be disposed in the recess in the concrete panel.
 2. An anchor for use in a concrete panel having a recess in a surface of the concrete panel, the anchor comprising: a forged unitary body comprising a shank comprising four substantially mutually perpendicular sides of equal width and forming a substantially square longitudinal cross-section, one end adapted to be embedable in the concrete panel, and an opposite end adapted to extend into the recess in the concrete panel; a foot connected to the one end of the shank and adapted to be embedable in the concrete panel, the foot having a substantially circular longitudinal cross-section; and a head connected to an opposite end of the shank and adapted to be disposed in the recess in the concrete panel, the head having a substantially circular longitudinal cross-section.
 3. The anchor of claim 2 wherein the head comprises: an outward extending substantially cylindrical portion with a diameter greater than the width of the sides of the shank; and a head transition having an outer end connected to the cylindrical portion and an inner end connected to the opposite end of the shank, the outer end having a diameter substantially equal to the diameter of the cylindrical portion and the inner end having a diameter substantially equal to the width of the sides of the shank.
 4. The anchor of claim 3 wherein the head transition has a centerline cross-sectional profile that is curvilinear between the ends of the head transition.
 5. The anchor of claim 4 wherein the head transition has a partial spherical shape between the ends of the head transition.
 6. The anchor of claim 2 wherein the foot comprises: an outer substantially cylindrical portion with a diameter greater than the width of the sides of the shank; and a foot transition having an outer end connected to the cylindrical portion and an inner end connected to the one end of the shank, the outer end having a diameter substantially equal to the diameter of the cylindrical portion and the inner end having a diameter substantially equal to the width of the sides of the shank.
 7. The anchor of claim 6 wherein the foot transition has a centerline cross-sectional profile that is curvilinear between the ends of the foot transition.
 8. The anchor of claim 7 wherein the foot transition has a partial spherical shape between the ends of the foot transition.
 9. A structural member comprising: a concrete panel comprising two substantially parallel major surfaces extending across a length and width of the concrete panel, at least one end surface extending between the opposing major surfaces and defining an end of the concrete panel, a recess disposed in one of the major surfaces of the concrete panel; and an anchor comprising a shank comprising four substantially mutually perpendicular planar surfaces forming a substantially square longitudinal cross-section extending over a length of the shank, one end disposed in the end of the concrete panel, and an opposite end extending from the one of the major surfaces and into the recess, a foot connected to the one end of the shank and disposed in the concrete panel, and a head connected to the opposite end of the shank and disposed in the recess in the concrete panel, the head being adapted to engage a lifting device for lifting the concrete panel. 